Drug Information on Frontline Plus for Dogs

Frontline is approved for puppies ages eight weeks and up.
Sly puppy in the park image by Lucki13 from Fotolia.com

Dogs of any age and lifestyle can contract fleas and ticks. Fleas and ticks cause discomfort, itching and illness. These parasitic insects are prolific, making it hard to eliminate them without the use of medications. There are a number of products available to treat and repel these parasites, including Frontline Plus. Speak to a licensed veterinary professional before starting your dog on flea medication to determine if Frontline Plus is the right choice.


Frontline Plus is a brand name, over-the-counter medication produced by the drug company Merial. It repels and kills fleas and ticks. Merial states that there are two active ingredients in Frontline Plus for dogs, fipronil and S-methoprene. Fipronil is a parasiticide that acts on the insects' nervous systems, causing paralysis and ultimately death. S-methoprene is an insect growth regulator (IGR) that inhibits the hatching of new flea eggs.


Frontline is packaged in a foil and plastic applicator package. The package contains a single dose formulated for a specific body weight. To apply, snap the perforated tip of the applicator off. Part the fur in the center of the dog's shoulder blades and squeeze the applicator, placing all of the medication in one spot. Frontline Plus should not be applied to the dog's fur. Because Frontline Plus for dogs is an oil-based solution, it is absorbed into the dog's hair follicles after application. Applying the medication between the shoulder blades means the dog is unable to chew at the spot and potentially ingest the medication, according to Applied Pharmacology for Veterinary Technicians.


Frontline Plus for Dogs is a once-a-month solution. It is relatively waterproof and does not need to be reapplied after dogs go swimming, walk in the rain or are bathed. The manufacturers of Frontline Plus state that it kills 100 percent of fleas within twelve hours of application. There are no known reactions between Frontline and other medications, according to Merial. Frontline Plus is safe for use in dogs over eight weeks of age and is safe to use in pregnant and nursing dogs.

Side Effects

Side effects from Frontline Plus are rare, according to Merial. Individual allergies or sensitivities may occur. Some dogs experience swelling, itching or irritation at the site of application due to the concentration of medication or carrier oils. Excessive salivation, diarrhea and lack of appetite were reported in clinical trials. Any adverse side effects should resolve within 12 to 24 hours of application. If the mild side effects persist for more than 12 to 24 hours, seek veterinary care.


If you suspect your dog is suffering from an allergic reaction to Frontline Plus, speak to a licensed veterinary medical professional immediately. Symptoms of an allergic reaction include swelling of the face, lips and tongue, itching, lethargy, uncoordinated movements, seizure, coma and death. Frontline Plus is not recommended for dogs that are extremely young or extremely old or dogs with compromised immune systems, according to the Clinical Textbook for Veterinary Technicians.